''package:cloud_firestore/src/firestore.dart': Failed assertion: line 49 pos 12: 'app != null': is not true

I have a compile error every time that I run my app. I have 3 views, Home Page, Hack Page, and Hack Screen. Hack Page: contains the card where I want to show my life hack of the particular category. Hacks Screen is the file where I control the firestore stuff (the hacks of each category). Home Page is the home of the app and it contains the list of categories in the form of cards.

My main goal is for the user to click on a particular category and then take the chosen category as collectionPath and put it in firestore.collection(collectionPath).snapshots()

For example:

In the Home Page the user clicks on the Travel Category --> it Navigates to Hack Screen with parameters of collectionPath as "travel" which is the collection name I have on firestore which contains all the travel categories hacks. --> it again Navigates to Hack Page where I have created a card and other option which then shows the Life Hacks of Travel one by one (controllable by button)

Problem: It's dropping this error and also when I remove the Hacks Screen from the process and directly navigate to Hack Page with random text it works fine so I think the problem is in the Hack Screen.

Note: I have initialized the Firebase and Cloud Firestore in the pubspec.yaml

Here's the Github link to my repo: https://github.com/pranjalchaplot/Hacks-For-Life for further convenience.

The error is:

D/ColorViewRootUtil(20907): nav bar mode ignore false downX 513 downY 380 mScreenHeight 1520 mScreenWidth 720 mStatusBarHeight 36 globalScale 1.125 nav mode 0 rotation 0 event MotionEvent { action=ACTION_DOWN, actionButton=0, id[0]=0, x[0]=513.0, y[0]=380.0, toolType[0]=TOOL_TYPE_FINGER, buttonState=0, classification=NONE, metaState=0, flags=0x0, edgeFlags=0x0, pointerCount=1, historySize=0, eventTime=42425289, downTime=42425289, deviceId=3, source=0x1002, displayId=0 }
D/ColorViewRootUtil(20907): nav bar mode ignore false downX 499 downY 621 mScreenHeight 1520 mScreenWidth 720 mStatusBarHeight 36 globalScale 1.125 nav mode 0 rotation 0 event MotionEvent { action=ACTION_DOWN, actionButton=0, id[0]=0, x[0]=499.0, y[0]=621.0, toolType[0]=TOOL_TYPE_FINGER, buttonState=0, classification=NONE, metaState=0, flags=0x0, edgeFlags=0x0, pointerCount=1, historySize=0, eventTime=42426777, downTime=42426777, deviceId=3, source=0x1002, displayId=0 }
I/flutter (20907): Another exception was thrown: 'package:cloud_firestore/src/firestore.dart': Failed assertion: line 49 pos 12: 'app != null': is not true.

Performing hot reload...
Reloaded 2 of 792 libraries in 662ms.
D/ColorViewRootUtil(20907): nav bar mode ignore false downX 427 downY 633 mScreenHeight 1520 mScreenWidth 720 mStatusBarHeight 36 globalScale 1.125 nav mode 0 rotation 0 event MotionEvent { action=ACTION_DOWN, actionButton=0, id[0]=0, x[0]=427.0, y[0]=633.0, toolType[0]=TOOL_TYPE_FINGER, buttonState=0, classification=NONE, metaState=0, flags=0x0, edgeFlags=0x0, pointerCount=1, historySize=0, eventTime=42507154, downTime=42507154, deviceId=3, source=0x1002, displayId=0 }
I/flutter (20907): Another exception was thrown: 'package:cloud_firestore/src/firestore.dart': Failed assertion: line 49 pos 12: 'app != null': is not true.

Performing hot reload...                                               -I/flutter (20907): ══╡ EXCEPTION CAUGHT BY WIDGETS 
LIBRARY ╞═══════════════════════════════════════════════════════════
I/flutter (20907): The following assertion was thrown building Builder(dirty):
I/flutter (20907): 'package:cloud_firestore/src/firestore.dart': Failed assertion: line 49 pos 12: 'app != null': is       
I/flutter (20907): not true.
I/flutter (20907):
I/flutter (20907): The relevant error-causing widget was:
I/flutter (20907):   MaterialApp   

The Hack_Page.dart:

import 'package:flutter/material.dart';
import 'package:google_fonts/google_fonts.dart';
import 'package:main/themes/style.dart';
import 'package:main/themes/theme_text.dart';

class HackPage extends StatelessWidget {
  final Color backgroundColor;
  final String hackText;

  const HackPage({
    Key key,
    @required this.backgroundColor,
    @required this.hackText,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Container(
          alignment: Alignment.center,
          child: Text(
            "Hacks For Life",
            style: GoogleFonts.oxygen(
              textStyle: TextStyle(
                fontWeight: FontWeight.bold,
              ),
            ),
          ),
        ),
        actions: [
          GestureDetector(
            onTap: () {},
            child: Container(
              padding: EdgeInsets.symmetric(horizontal: 16),
              child: Icon(Icons.share_outlined),
            ),
          )
        ],
      ),
      body: Container(
        child: Column(
          children: [
            Container(
              margin: EdgeInsets.only(top: 35),
              child: Card(
                color: backgroundColor,
                margin: EdgeInsets.only(left: 20, right: 20),
                child: Column(
                  mainAxisAlignment: MainAxisAlignment.end,
                  mainAxisSize: MainAxisSize.min,
                  crossAxisAlignment: CrossAxisAlignment.stretch,
                  children: [
                    Stack(
                      children: [
                        Container(
                          height: 400,
                          width: 360,
                          alignment: Alignment.center,
                          child: ListTile(
                            title: Text(
                              hackText,
                              style: ThemeText.headline,
                              textAlign: TextAlign.center,
                            ),
                            tileColor: Colors.transparent,
                          ),
                        ),
                      ],
                    ),
                  ],
                ),
                shape: RoundedRectangleBorder(
                  borderRadius: BorderRadius.circular(10.0),
                ),
              ),
            ),
            SizedBox(
              height: 45,
            ),
            Row(
              mainAxisAlignment: MainAxisAlignment.center,
              children: [
                GestureDetector(
                  onTap: () {},
                  child: Column(
                    children: [
                      Container(
                          padding: EdgeInsets.symmetric(horizontal: 26),
                          child: Icon(
                            Icons.chevron_left_rounded,
                            color: Colors.white,
                            size: 50,
                          )),
                      Container(
                        margin: EdgeInsets.only(top: 5),
                        child: Text(
                          "Previous",
                          style: simpleText(),
                        ),
                      ),
                    ],
                  ),
                ),
                GestureDetector(
                  onTap: () {},
                  child: Column(
                    children: [
                      Container(
                          padding: EdgeInsets.symmetric(horizontal: 26),
                          child: Icon(
                            Icons.chevron_right_rounded,
                            color: Colors.white,
                            size: 50,
                          )),
                      Container(
                        margin: EdgeInsets.only(top: 5),
                        child: Text("Next", style: simpleText()),
                      )
                    ],
                  ),
                )
              ],
            )
          ],
        ),
      ),
    );
  }
}

The Hack_Screen.dart:

import 'package:flutter/material.dart';
import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:main/views/hack_page.dart';
import 'package:random_color/random_color.dart';

class HackScreen extends StatelessWidget {
  final FirebaseFirestore _firestore = FirebaseFirestore.instanceFor();
  final RandomColor _randomColor = RandomColor();

  final String collectionPath;

  HackScreen({
    Key key,
    @required this.collectionPath,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: StreamBuilder(
        stream: _firestore.collection(collectionPath).snapshots(),
        builder: (context, snapshot) {
          if (!snapshot.hasData) return _LoadingIndicator();
          return PageView.builder(
            itemCount: snapshot.data.docs.length,
            itemBuilder: (context, index) {
              final document = snapshot.data.docs[index];
              return HackPage(
                backgroundColor: _randomColor.randomColor(
                  colorBrightness: ColorBrightness.dark,
                ),
                hackText: document['hack'],
              );
            },
          );
        },
      ),
    );
  }
}

class _LoadingIndicator extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Center(
      child: CircularProgressIndicator(),
    );
  }
}

The Error After Calling the Firebase Auth:

I/flutter (20167): ══╡ EXCEPTION CAUGHT BY RENDERING LIBRARY ╞═════════════════════════════════════════════════════════
I/flutter (20167): The following assertion was thrown during performLayout():
I/flutter (20167): RenderCustomMultiChildLayoutBox object was given an infinite size during layout.
I/flutter (20167): This probably means that it is a render object that tries to be as big as possible, but it was put
I/flutter (20167): inside another render object that allows its children to 
pick their own size.
I/flutter (20167): The nearest ancestor providing an unbounded height constraint is: RenderIndexedSemantics#b3286 relayoutBoundary=up3 NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE:
I/flutter (20167):   creator: IndexedSemantics ← NotificationListener<KeepAliveNotification> ← KeepAlive ←
I/flutter (20167):     AutomaticKeepAlive ← KeyedSubtree ← SliverList ← MediaQuery ← SliverPadding ← Viewport ←
I/flutter (20167):     IgnorePointer-[GlobalKey#873d3] ← Semantics ← _PointerListener ← ⋯
I/flutter (20167):   parentData: index=0; layoutOffset=0.0 (can use size)   
I/flutter (20167):   constraints: BoxConstraints(w=360.0, 0.0<=h<=Infinity) 
I/flutter (20167):   semantic boundary
I/flutter (20167):   size: MISSING
I/flutter (20167):   index: 0
I/flutter (20167): The constraints that applied to the RenderCustomMultiChildLayoutBox were:
I/flutter (20167):   BoxConstraints(w=360.0, 0.0<=h<=Infinity)
I/flutter (20167): The exact size it was given was:
I/flutter (20167):   Size(360.0, Infinity)
I/flutter (20167): See https://flutter.dev/docs/development/ui/layout/box-constraints for more information.
I/flutter (20167): 
I/flutter (20167): The relevant error-causing widget was:
I/flutter (20167):   Scaffold
I/flutter (20167):   file:///D:/Work/Learning/Learning%20Flutter/LifeHacks_app/main/lib/views/hack_page.dart:18:12
I/flutter (20167): 
I/flutter (20167): When the exception was thrown, this was the stack:
I/flutter (20167): #0      RenderBox.debugAssertDoesMeetConstraints.<anonymous closure> (package:flutter/src/rendering/box.dart:2060:9)
I/flutter (20167): #1      RenderBox.debugAssertDoesMeetConstraints (package:flutter/src/rendering/box.dart:2128:6)
I/flutter (20167): #2      RenderBox.size=.<anonymous closure> (package:flutter/src/rendering/box.dart:1846:7)
I/flutter (20167): #3      RenderBox.size= (package:flutter/src/rendering/box.dart:1848:6)
I/flutter (20167): #4      RenderCustomMultiChildLayoutBox.performLayout (package:flutter/src/rendering/custom_layout.dart:401:5)
I/flutter (20167): #5      RenderObject.layout (package:flutter/src/rendering/object.dart:1777:7)
I/flutter (20167): #6      RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:111:14)
I/flutter (20167): #7      RenderObject.layout (package:flutter/src/rendering/object.dart:1777:7)
I/flutter (20167): #8      RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:111:14)
I/flutter (20167): #9      _RenderCustomClip.performLayout (package:flutter/src/rendering/proxy_box.dart:1306:11)
I/flutter (20167): #10     RenderObject.layout (package:flutter/src/rendering/object.dart:1777:7)
I/flutter (20167): #11     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:111:14)
I/flutter (20167): #12     RenderObject.layout (package:flutter/src/rendering/object.dart:1777:7)
I/flutter (20167): #13     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:111:14)
I/flutter (20167): #14     RenderObject.layout (package:flutter/src/rendering/object.dart:1777:7)
I/flutter (20167): #15     RenderSliverList.performLayout (package:flutter/src/rendering/sliver_list.dart:213:28)
I/flutter (20167): #16     RenderObject.layout (package:flutter/src/rendering/object.dart:1777:7)
I/flutter (20167): #17     RenderSliverEdgeInsetsPadding.performLayout (package:flutter/src/rendering/sliver_padding.dart:139:12)
I/flutter (20167): #18     RenderSliverPadding.performLayout (package:flutter/src/rendering/sliver_padding.dart:374:11)
I/flutter (20167): #19     RenderObject.layout (package:flutter/src/rendering/object.dart:1777:7)
I/flutter (20167): #20     RenderViewportBase.layoutChildSequence (package:flutter/src/rendering/viewport.dart:507:13)
I/flutter (20167): #21     RenderViewport._attemptLayout (package:flutter/src/rendering/viewport.dart:1561:12)
I/flutter (20167): #22     RenderViewport.performLayout (package:flutter/src/rendering/viewport.dart:1470:20)
I/flutter (20167): #23     RenderObject.layout (package:flutter/src/rendering/object.dart:1777:7)
I/flutter (20167): #24     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:111:14)
I/flutter (20167): #25     RenderObject.layout (package:flutter/src/rendering/object.dart:1777:7)
I/flutter (20167): #26     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:111:14)
I/flutter (20167): #27     RenderObject.layout (package:flutter/src/rendering/object.dart:1777:7)
I/flutter (20167): #28     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:111:14)
I/flutter (20167): #29     RenderObject.layout (package:flutter/src/rendering/object.dart:1777:7)
I/flutter (20167): #30     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:111:14)
I/flutter (20167): #31     RenderObject.layout (package:flutter/src/rendering/object.dart:1777:7)
I/flutter (20167): #32     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:111:14)
I/flutter (20167): #33     RenderObject.layout (package:flutter/src/rendering/object.dart:1777:7)
I/flutter (20167): #34     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:111:14)
I/flutter (20167): #35     RenderObject.layout (package:flutter/src/rendering/object.dart:1777:7)
I/flutter (20167): #36     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:111:14)
I/flutter (20167): #37     RenderObject.layout (package:flutter/src/rendering/object.dart:1777:7)
I/flutter (20167): #38     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:111:14)
I/flutter (20167): #39     RenderObject.layout (package:flutter/src/rendering/object.dart:1777:7)
I/flutter (20167): #40     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:111:14)
I/flutter (20167): #41     RenderObject.layout (package:flutter/src/rendering/object.dart:1777:7)
I/flutter (20167): #42     MultiChildLayoutDelegate.layoutChild (package:flutter/src/rendering/custom_layout.dart:171:12)
I/flutter (20167): #43     _ScaffoldLayout.performLayout (package:flutter/src/material/scaffold.dart:498:7)
I/flutter (20167): #44     MultiChildLayoutDelegate._callPerformLayout (package:flutter/src/rendering/custom_layout.dart:243:7)
I/flutter (20167): #45     RenderCustomMultiChildLayoutBox.performLayout (package:flutter/src/rendering/custom_layout.dart:402:14)
I/flutter (20167): #46     RenderObject._layoutWithoutResize (package:flutter/src/rendering/object.dart:1634:7)
I/flutter (20167): #47     PipelineOwner.flushLayout (package:flutter/src/rendering/object.dart:884:18)
I/flutter (20167): #48     RendererBinding.drawFrame (package:flutter/src/rendering/binding.dart:444:19)
I/flutter (20167): #49     WidgetsBinding.drawFrame (package:flutter/src/widgets/binding.dart:907:13)
I/flutter (20167): #50     RendererBinding._handlePersistentFrameCallback (package:flutter/src/rendering/binding.dart:310:5)
I/flutter (20167): #51     SchedulerBinding._invokeFrameCallback (package:flutter/src/scheduler/binding.dart:1117:15)
I/flutter (20167): #52     SchedulerBinding.handleDrawFrame (package:flutter/src/scheduler/binding.dart:1055:9)
I/flutter (20167): #53     SchedulerBinding._handleDrawFrame (package:flutter/src/scheduler/binding.dart:971:5)
I/flutter (20167): #57     _invoke (dart:ui/hooks.dart:251:10)
I/flutter (20167): #58     _drawFrame (dart:ui/hooks.dart:209:3)
I/flutter (20167): (elided 3 frames from dart:async)
I/flutter (20167):
I/flutter (20167): The following RenderObject was being processed when the exception was fired: RenderCustomMultiChildLayoutBox#e1c48 relayoutBoundary=up7 NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE:
I/flutter (20167):   creator: CustomMultiChildLayout ← AnimatedBuilder ← DefaultTextStyle ← AnimatedDefaultTextStyle ←
I/flutter (20167):     _InkFeatures-[GlobalKey#87cbd ink renderer] ← NotificationListener<LayoutChangedNotification> ←
I/flutter (20167):     PhysicalModel ← AnimatedPhysicalModel ← Material ← PrimaryScrollController ← _ScaffoldScope ←
I/flutter (20167):     Scaffold ← ⋯
I/flutter (20167):   parentData: <none> (can use size)
I/flutter (20167):   constraints: BoxConstraints(w=360.0, 0.0<=h<=Infinity) 
I/flutter (20167):   size: Size(360.0, Infinity)
I/flutter (20167): This RenderObject had the following descendants (showing 
up to depth 5):
I/flutter (20167):     child 1: RenderFlex#c6502 NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
I/flutter (20167):       child 1: RenderPadding#61c12 NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
I/flutter (20167):         child: RenderSemanticsAnnotations#5631c NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
I/flutter (20167):           child: RenderPadding#9c899 NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
I/flutter (20167):             child: RenderPhysicalShape#5fb12 NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
I/flutter (20167):       child 2: RenderConstrainedBox#38281 NEEDS-LAYOUT NEEDS-PAINT
I/flutter (20167):       child 3: RenderFlex#2b713 NEEDS-LAYOUT NEEDS-PAINT 
NEEDS-COMPOSITING-BITS-UPDATE
I/flutter (20167):         child 1: RenderSemanticsGestureHandler#a2514 NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
I/flutter (20167):           child: RenderPointerListener#d53c9 NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
I/flutter (20167):             child: RenderFlex#53d86 NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
I/flutter (20167):         child 2: RenderSemanticsGestureHandler#fbe23 NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
I/flutter (20167):           child: RenderPointerListener#eda8e NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
I/flutter (20167):             child: RenderFlex#e1f6c NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
I/flutter (20167):     child 2: RenderConstrainedBox#05703 NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
I/flutter (20167):       child: RenderSemanticsAnnotations#d4582 NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
I/flutter (20167):         child: RenderAnnotatedRegion<SystemUiOverlayStyle>#3c823 NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
I/flutter (20167):           child: RenderPhysicalModel#09da9 NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
I/flutter (20167):             child: _RenderInkFeatures#bfd47 NEEDS-LAYOUT 
NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
I/flutter (20167):     child 3: RenderStack#f13cd NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
I/flutter (20167):       child 1: RenderTransform#9e397 NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
I/flutter (20167):         child: RenderTransform#23b82 NEEDS-LAYOUT NEEDS-PAINT
I/flutter (20167): ════════════════════════════════════════════════════════════════════════════════════════════════════
I/flutter (20167): Another exception was thrown: _RenderInkFeatures object was given an infinite size during layout.
W/om.example.mai(20167): Accessing hidden field Ljava/net/Socket;->impl:Ljava/net/SocketImpl; (greylist, reflection, allowed)
I/flutter (20167): Another exception was thrown: RenderPhysicalModel object 
was given an infinite size during layout.
W/om.example.mai(20167): Accessing hidden method Ldalvik/system/CloseGuard;->get()Ldalvik/system/CloseGuard; (greylist,core-platform-api, linking, allowed)
I/flutter (20167): Another exception was thrown: RenderRepaintBoundary object was given an infinite size during layout.
W/om.example.mai(20167): Accessing hidden method Ldalvik/system/CloseGuard;->open(Ljava/lang/String;)V (greylist,core-platform-api, linking, allowed)   
W/om.example.mai(20167): Accessing hidden field Ljava/io/FileDescriptor;->descriptor:I (greylist, JNI, allowed)
I/flutter (20167): Another exception was thrown: RenderIndexedSemantics object was given an infinite size during layout.
W/om.example.mai(20167): Accessing hidden method Ljava/security/spec/ECParameterSpec;->setCurveName(Ljava/lang/String;)V (greylist, reflection, allowed)W/om.example.mai(20167): Accessing hidden method Ldalvik/system/BlockGuard;->getThreadPolicy()Ldalvik/system/BlockGuard$Policy; (greylist,core-platform-api, linking, allowed)
W/om.example.mai(20167): Accessing hidden method Ldalvik/system/BlockGuard$Policy;->onNetwork()V (greylist, linking, allowed)
W/om.example.mai(20167): Accessing hidden method Lsun/misc/Unsafe;->getObject(Ljava/lang/Object;J)Ljava/lang/Object; (greylist, linking, allowed)       
W/om.example.mai(20167): Accessing hidden method Lsun/misc/Unsafe;->getInt(Ljava/lang/Object;J)I (greylist, linking, allowed)
W/om.example.mai(20167): Accessing hidden method Lsun/misc/Unsafe;->getObject(Ljava/lang/Object;J)Ljava/lang/Object; (greylist, linking, allowed)       
W/om.example.mai(20167): Accessing hidden method Lsun/misc/Unsafe;->putInt(Ljava/lang/Object;JI)V (greylist, linking, allowed)
W/om.example.mai(20167): Accessing hidden method Lsun/misc/Unsafe;->putObject(Ljava/lang/Object;JLjava/lang/Object;)V (greylist, linking, allowed)      
W/om.example.mai(20167): Accessing hidden method Lsun/misc/Unsafe;->putObject(Ljava/lang/Object;JLjava/lang/Object;)V (greylist, linking, allowed)      
W/om.example.mai(20167): Accessing hidden method Lsun/misc/Unsafe;->putLong(Ljava/lang/Object;JJ)V (greylist, linking, allowed)
W/om.example.mai(20167): Accessing hidden method Lsun/misc/Unsafe;->putObject(Ljava/lang/Object;JLjava/lang/Object;)V (greylist, linking, allowed)      
W/om.example.mai(20167): Accessing hidden method Lsun/misc/Unsafe;->putObject(Ljava/lang/Object;JLjava/lang/Object;)V (greylist, linking, allowed)      
W/om.example.mai(20167): Accessing hidden method Lsun/misc/Unsafe;->putLong(Ljava/lang/Object;JJ)V (greylist, linking, allowed)
W/om.example.mai(20167): Accessing hidden method Lsun/misc/Unsafe;->putObject(Ljava/lang/Object;JLjava/lang/Object;)V (greylist, linking, allowed)
W/om.example.mai(20167): Accessing hidden method Lsun/misc/Unsafe;->putLong(Ljava/lang/Object;JJ)V (greylist, linking, allowed)
W/om.example.mai(20167): Accessing hidden method Lsun/misc/Unsafe;->getLong(Ljava/lang/Object;J)J (greylist,core-platform-api, linking, allowed)
W/om.example.mai(20167): Accessing hidden method Lsun/misc/Unsafe;->getLong(Ljava/lang/Object;J)J (greylist,core-platform-api, linking, allowed)
W/om.example.mai(20167): Accessing hidden method Lsun/misc/Unsafe;->putObject(Ljava/lang/Object;JLjava/lang/Object;)V (greylist, linking, allowed)
W/om.example.mai(20167): Accessing hidden method Lsun/misc/Unsafe;->putObject(Ljava/lang/Object;JLjava/lang/Object;)V (greylist, linking, allowed)
W/om.example.mai(20167): Accessing hidden method Lsun/misc/Unsafe;->getObject(Ljava/lang/Object;J)Ljava/lang/Object; (greylist, linking, allowed)
W/om.example.mai(20167): Accessing hidden method Lsun/misc/Unsafe;->putLong(Ljava/lang/Object;JJ)V (greylist, linking, allowed)
W/om.example.mai(20167): Accessing hidden method Lsun/misc/Unsafe;->putObject(Ljava/lang/Object;JLjava/lang/Object;)V (greylist, linking, allowed)
W/om.example.mai(20167): Accessing hidden method Lsun/misc/Unsafe;->putObject(Ljava/lang/Object;JLjava/lang/Object;)V (greylist, linking, allowed)
W/om.example.mai(20167): Accessing hidden method Lsun/misc/Unsafe;->putLong(Ljava/lang/Object;JJ)V (greylist, linking, allowed)


Solution 1:[1]

The first issue here is with the way Firestore is being initialized. Instead of FirebaseFirestore.instanceFor(), it should be FirebaseFirestore.instance as previously mentioned in the comments.

final FirebaseFirestore _firestore = FirebaseFirestore.instance;

The second issue has something to do with the Widgets on screen, base from the error RenderCustomMultiChildLayoutBox object was given an infinite size during layout.

It looks like the screen tries to render a Widget with an infinite dimension. Trying to add a SizedBox as constraints or defining width/height on the Widget usually solves this issue.

Sources

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Source: Stack Overflow

Solution Source
Solution 1 Omatt